Rear Pinion Flange bolts loose

[stang980]

Was putting some jack rails on my 2019 MT82 manual mustang. While I was under there I slid to the rear of the car to just do a visual inspection of the differential, axles, etc. Noticed a very loose bolt on the pinion Flange, where it connects to the rear differential from the drive shaft. I have been having some 30 to 40mph vibrations, but only in that mph range. I figured this was a likely cause. When I checked the other five bolts, they were loose as well. Could turn them with my fingers. Tightened everything best I could (don't have a torque wrench capable of the 41 foot pound).

Took it for a drive and still experienced the vibration. Took it back home and got back under it and observed the same bolt was practically hanging in by 2 threads and was all the way out, worse than before. Rest of bolts were loose as well again.

Anyone experienced this or know what is going on? My test drive was less than a mile.

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[stang980]

Just in case this is searched one day by someone in similar situation.

The problem was solved. These bolts are not reusable. They were taken out, by Ford, when I had an engine replacement. Apparently they were reused. This is why they won't stay tight. New bolts ordered.

 

[WildHorse]

Apparently they were reused. This is why they won't stay tight. New bolts ordered.

Well now, I just re-loctite my old drive shaft to pinion adaptor bolts.

 

[stang980]

Well now, I just re-loctite my old drive shaft to pinion adaptor bolts.

That was my original plan. But I just figured I'd let Ford do it since they have the tool to torque them properly. My tool doesn't have the torque capability these bolts call for. I went to Ford, its under warranty, and just told them to lock tight them and torque them to 41 foot pounds. After a few hours the tech came and said he couldn't do that because these bolts weren't reusable. They admitted they messed it up when they reused them the first time and said they'd put new bolts in...I'd have been fine with lock tight and a proper torque...but won't turn down new bolts for free.

 

[Kong76]

Man I had my transmission replaced a while back and get a pretty good vibe at speeds. I have had the tires balanced multiple times. I am going to take a look at this Sunday. Thanks for the heads up.

 

[Granthenneke]

I had this happen to me with my 2018 MT-82. Took it to the dealer and they said that I need a new driveshaft. We're new bolts all that were needed for the fix? All 6 bolts that connected the driveshaft to the pinion were lose. One even came out by hand.

 

[Cobra Jet]

Does it state in the Ford Shop Manual those bolts are single use only? That's news to many if it is, because on prior Mustangs, these bolts have always been reusable if removed.

 

[Granthenneke]

Does it state in the Ford Shop Manual those bolts are single use only? That's news to many if it is, because on prior Mustangs, these bolts have always been reusable if removed.

It does state that it's one time use. But I've heard of many just re applying the loctite and throwing it back in.

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